1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof and, more particularly, to a coolable semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
Demands have arisen for downsizing and high integration of semiconductor integrated circuits in various fields. To meet these demands, the integration degree and performance of semiconductor integrated circuits have reliably improved as the microfabrication of semiconductor elements and processes advance and the performance of semiconductor elements improves.
On the other hand, the improvements in integration degree and performance of semiconductor integrated circuits largely increase the power consumption of the semiconductor integrated circuits. In addition, the heat generated by this increase in power consumption largely deteriorates the performance of semiconductor elements and the reliability or safety of semiconductor integrated circuits.
The key to the solution of this heat problem of semiconductor integrated circuits is generally the efficiency of radiation of heat from the lower surface of a semiconductor substrate. Therefore, it is being attempted to use low-thermal-resistance materials or improve the structure of a heat pipe or the like for efficient heat radiation.
Unfortunately, the cooling techniques are not well compensating for the increasing power consumption. Accordingly, the temperature of element regions formed in a semiconductor substrate rises, and as a consequence semiconductor elements and therefore a semiconductor integrated circuit malfunction. Also, the heat problem produces a region where the temperature locally rises in a semiconductor integrated circuit. Consequently, this semiconductor integrated circuit can be used only within the range in which the performance is limited, e.g., the voltage is controlled if the temperature rises.
As a technique related to this field, a semiconductor device having a microchannel for supplying a refrigerant to the lower surface opposite to the element formation surface of a substrate is disclosed (U.S. Pat. No. 5,998,240).